Drag free sliding caliper disc brake bushing

Abstract

A caliper housing is slidably mounted on support pins with rubber-like bushings. Each bushing is compressed in a housing groove when the disc brake is actuated to move the housing in the brake apply direction. The bushing has a toroidal main body and a series of circumferentially spaced axially extending protrusions. The main body grips the cylindrical surface of a pin in slip-stick relation. Upon brake actuation the protrusions are compressed. Upon brake release they return to their original configuration, moving the housing on the pins in the release direction to provide zero brake drag of the brake shoes on the disc. The bushing main body slips relative to the pins only when sliding movement of the caliper housing during brake actuation is sufficient to require adjustment of the brake release position of the caliper housing relative to the support pins.

What is claimed is: 
     
       1. In a drag-free sliding caliper disc brake having a cylindrical support member;   a caliper housing member having a cylindrical opening therethrough through which said support member extends;   one of said members having a groove formed therein defined by a bottom wall and side walls and opening toward the other of said members within said cylindrical opening; the improvement comprising:   an annular resilient rubber-like bushing received in said groove, said bushing having a toroidal main body engaging said groove bottom wall and the cylindrical surface of said other member in a grip-slip relation, said bushing having a series of circumferentially spaced resilient protrusions extending from said main body in an axial direction and normally engaging one of said groove side walls and radially spaced from said other member so as to have no radial loading thereon;   said bushing protrusions being axially compressed upon brake actuation by sliding movement of said caliper housing member relative to said support member in the brake actuating direction, said bushing protrusions upon brake release expanding axially and moving said caliper housing member relative to said support member in the brake releasing direction until there is no brake drag, said bushing main body slipping relative to said other member during brake actuation only when the sliding movement is sufficient to require adjustment of the brake release position of said caliper housing member relative to said support member.   
     
     
       2. A bushing assembly comprising: concentric radially spaced inner and outer sleeve members subject to axial relative movements during normal usage, one of said sleeve members having a groove therein defined by a bottom surface and side walls and opening toward the other of said sleeve members; and   an annular resilient rubber-like bushing having a toroidal main body and a series of circumferentially spaced resilient protrusions extending from said main body along axes lying in a formation defined by a surface of revolution generated about the center axis of said toroidal main body, each of said protrusions having a smaller transverse thickness than the transverse thickness of said toroidal main body, said protrusions having free ends remote from said toroidal main body engageable with one of said groove side walls, said protrusions being normally radially spaced from said groove bottom surface and the surface of the other of said sleeve members so as to have no radial loading thereon, said toroidal main body engaging said groove bottom surface and the surface of the other of said sleeve members and engageable with the other of said groove side walls, said protrusions acting as compression springs and storing energy upon relative movement of said sleeve members in one axial direction and releasing the stored energy to at least assist in causing relative movement of said sleeve members in the opposite axial direction, said toroidal main body resistably slipping axially relative to the surface of the other of said sleeve members only when relative axial movement of said sleeve members in the one axial direction is sufficient to cause such slipping.   
     
     
       3. A bushing assembly comprising: concentric radially spaced inner and outer sleeve members subject to axial relative movements during normal usage, one of said sleeve members having a groove therein defined by a bottom surface and side walls and opening toward the other of said sleeve members; and   an annular resilient rubber-like bushing having a toroidal main body and a series of circumferentially spaced resilient protrusions extending from said main body along axes lying in a formation defined by a surface of revolution generated about the center axis of said toroidal main body and passing through the annular axis of said toroidal main body, each of said protrusions having a smaller transverse thickness than the transverse thickness of said toroidal main body, said protrusions having free ends remote from said toroidal main body engageable with one of said groove side walls, said protrusions being normally radially spaced from said groove bottom surface and the surface of the other of said sleeve members so as to have no radial loading thereon, said toroidal main body engaging said groove bottom surface and the surface of the other of said sleeve members and engageable with the other of said groove side walls, said protrusions acting as compression springs and storing energy upon relative movement of said sleeve members in one axial direction and releasing the stored energy to at least assist in causing relative movement of said sleeve members in the opposite axial direction, said toroidal main body resistably slipping axially relative to the surface of the other of said sleeve members only when relative axial movement of said sleeve members in the one axial direction is sufficient to cause such slipping.   
     
     
       4. A bushing assembly comprising: concentric radially spaced inner and outer sleeve members subject to axial relative movements during normal usage, one of said sleeve members having a groove therein defined by a bottom surface and side walls and opening toward the other of said sleeve members; and   an annular resilient rubber-like bushing having a toroidal main body and a series of circumferentially spaced resilient protrusions extending from said main body along axes lying in a formation defined by a right circular cylindrical surface of revolution generated about the center axis of said toroidal main body and passing through the annular axis of said toroidal main body, each of said protrusions having a smaller transverse thickness than the transverse thickness of said toroidal main body, said protrusions having free ends remote from said toroidal main body engageable with one of said groove side walls, said protrusions being normally radially spaced from said groove bottom surface and the surface of the other of said sleeve members so as to have no radial loading thereon, said toroidal main body engaging said groove bottom surface and the surface of the other of said sleeve members and engageable with the other of said groove side walls, said protrusions acting as compression springs and storing energy upon relative movement of said sleeve members in one axial direction and releasing the stored energy to at least assist in causing relative movement of said sleeve members in the opposite axial direction, said toroidal main body resistably slipping axially relative to the surface of the other of said sleeve members only when relative axial movement of said sleeve members in the one axial direction is sufficient to cause such slipping.